Optical crosstalk mitigation for a detector array in an optical receiver

ABSTRACT

A method of manufacturing a photodetector device is provided. The method includes providing a photodetector array comprising an array of photodetectors and a plurality of metal structures arranged laterally between photodetectors of the array of photodetectors, wherein the photodetectors are co-planar with the plurality of metal structures, and wherein the plurality of metal structures are arranged in a first pattern; applying an antireflective coating to a surface of a transparent substrate, the antireflective coating being patterned according to a second pattern that matches the first pattern; aligning the transparent substrate over the photodetector array such that the first pattern is aligned with the second pattern; and coupling the transparent substrate to the photodetector array such that the antireflective coating covers the plurality of metal structures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/590,702 filed Oct. 2, 2019, which is incorporated by reference as iffully set forth.

FIELD

The present disclosure relates generally to a detector array for anoptical receiver and to methods for manufacturing the same.

BACKGROUND

Optical receivers are used in cameras and image sensors, such as LightDetection and Ranging (LIDAR) receivers. Optical receivers may use adetector array made up of an array of photodetectors, such asphotodiodes, for receiving and measuring light that is reflected fromobjects in an environment. For example, LIDAR is a remote sensing methodthat uses light in the form of a pulsed laser to measure ranges(variable distances) to one or more objects in a field of view. Inparticular, light is transmitted towards one or more objects. Singlephotodetectors or arrays of photodetectors receive reflections fromobjects illuminated by the light, and the time it takes for thereflections to arrive at various sensors in the photodetector array isdetermined. This is also referred to as measuring time-of-flight (ToF).LIDAR systems form depth measurements and make distance measurements bymapping the distance to objects based on the time-of-flightcomputations. Thus, the time-of-flight computations can create distanceand depth maps, which may be used to generate images. Other types ofcamera systems may also use photodetectors for generating images basedon detected light.

Optical receivers typically include a receiver optics and a detectorarray. The receiver optics initially receives the light and directs thelight towards the detector array. The detector array typically includesmultiple sensitive parts in the way of the photodetectors andnon-sensitive part in the way of metal structures formed around eachsensitive part. The metal structures may include metal lines that areused to read out electrical signals generated by the photodetectors.While the sensitive parts absorb light, the metal structures have areflectivity that may exceed 70%. As a result, some light received atthe detector array may be reflected back by the metal structures towardsthe receiver optics, which may in turn reflect the light back towards adifferent region of the detector array by surface residual reflection.This “bouncing” light between the detector array and the receiver opticscauses optical crosstalk between neighboring photodetectors and maynegatively impact the accuracy of the measured light and the resultantimage.

Therefore, an improved device having a detector array that mitigatesoptical crosstalk may be desirable.

SUMMARY

Embodiments provide a method of manufacturing a photodetector device.The method includes providing a photodetector array comprising an arrayof photodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; applying anantireflective coating to a surface of a transparent substrate, theantireflective coating being patterned according to a second patternthat matches the first pattern; aligning the transparent substrate overthe photodetector array such that the first pattern is aligned with thesecond pattern; and coupling the transparent substrate to thephotodetector array such that the antireflective coating covers theplurality of metal structures.

Embodiments provide a photodetector device that includes a photodetectorarray including an array of photodetectors and a plurality of metalstructures arranged between photodetectors of the array ofphotodetectors, wherein the plurality of metal structures are arrangedin a first pattern; and a transparent substrate including a plurality oftrenches being patterned according to a second pattern that matches thefirst pattern and at least partially filled with an antireflectivematerial such that the antireflective material takes on the secondpattern. The transparent substrate and the photodetector array arecoupled together such that the first pattern is aligned with the secondpattern and the antireflective material covers the plurality of metalstructures.

Embodiments provide a method of manufacturing a photodetector device.The method includes providing a photodetector array including an arrayof photodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; forming a plurality oftrenches in a transparent substrate, the plurality of trenches beingpatterned according to a second pattern that matches the first pattern;at least partially filing the plurality of trenches with anantireflective material such that the antireflective material takes onthe second pattern; aligning the transparent substrate over thephotodetector array such that the first pattern is aligned with thesecond pattern; and coupling the transparent substrate to thephotodetector array such that the antireflective material covers theplurality of metal structures.

Embodiments provide a photodetector device that includes a photodetectorarray including an array of photodetectors and a plurality of metalstructures arranged between photodetectors of the array ofphotodetectors, wherein the plurality of metal structures are arrangedin a first pattern; and a transparent substrate including a plurality ofdiffusion structures being patterned according to a second pattern thatmatches the first pattern, wherein each of the plurality of diffusionstructures is configured to redirect light that is incident thereon. Thetransparent substrate and the photodetector array are coupled togethersuch that the first pattern is aligned with the second pattern and theplurality of diffusion structures covers the plurality of metalstructures.

Embodiments provide a method of manufacturing a photodetector device.The method includes providing a photodetector array including an arrayof photodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; forming a plurality ofdiffusion structures in a transparent substrate, the plurality ofdiffusion structures being patterned according to a second pattern thatmatches the first pattern, wherein each of the plurality of diffusionstructures is configured to redirect light that is incident thereon;aligning the transparent substrate over the photodetector array suchthat the first pattern is aligned with the second pattern; and couplingthe transparent substrate to the photodetector array such that theplurality of diffusion structures covers the plurality of metalstructures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are described herein making reference to the appendeddrawings.

FIGS. 1A-1C illustrate a process of manufacturing a photodetector deviceaccording to one or more embodiments;

FIG. 2 illustrates a cross-sectional view of an assembled photodetectordevice according to one or more embodiments;

FIG. 3 illustrates a cross-sectional view of an assembled photodetectordevice according to one or more embodiments;

FIGS. 4A-4C illustrate a process of manufacturing a photodetector deviceaccording to one or more embodiments; and

FIG. 5 illustrates a cross-sectional view of an assembled photodetectordevice according to one or more embodiments.

DETAILED DESCRIPTION

In the following, various embodiments will be described in detailreferring to the attached drawings, where like reference numerals referto like elements throughout. It should be noted that these embodimentsserve illustrative purposes only and are not to be construed aslimiting. For example, while embodiments may be described as comprisinga plurality of features or elements, this is not to be construed asindicating that all these features or elements are needed forimplementing embodiments. Instead, in other embodiments, some of thefeatures or elements may be omitted, or may be replaced by alternativefeatures or elements. Additionally, further features or elements inaddition to the ones explicitly shown and described may be provided, forexample conventional components of sensor devices.

Features from different embodiments may be combined to form furtherembodiments, unless specifically noted otherwise. Variations ormodifications described with respect to one of the embodiments may alsobe applicable to other embodiments. In some instances, well-knownstructures and devices are shown in block diagram form rather than indetail in order to avoid obscuring the embodiments.

In the following detailed description reference is made to theaccompanying drawings, which form a part hereof and in which areillustrated by way of illustration example embodiments. In this regard,directional terminology such as “top”, “bottom”, “front”, “back”,“leading”, “trailing” etc. is used with reference to the orientation ofthe Figures being described. Similarly, the terms “above” and “below” asused in this specification may describe a relative location of astructural feature to another. The term “horizontal” as used in thisspecification intends to describe an orientation substantially parallelto a first or main surface of a substrate or body. The term “vertical”as used in this specification intends to describe an orientation whichis substantially arranged perpendicular to the first or main surface,i.e. parallel to the normal direction of the first surface of thesubstrate or body.

Since components of the embodiments can be positioned in a number ofdifferent orientations, the directional terminology is used for purposesof illustration and is in no way limiting. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope defined by the claims.

Embodiments relate to optical sensors and optical sensor systems and toobtaining information about optical sensors and optical sensor systems.A sensor may refer to a component which converts a physical quantity tobe measured to an electric signal, for example a current signal or avoltage signal. The physical quantity may, for example, compriseelectromagnetic radiation, such as visible light, infrared (IR)radiation, or other type of illumination signal, a current, or avoltage, but is not limited thereto. For example, an image sensor may bea silicon chip inside a camera that converts photons of light comingfrom a lens into voltages. The larger the active area of the sensor, themore light that can be collected to create an image.

A sensor device as used herein may refer to a device which comprises asensor and further components, for example biasing circuitry, ananalog-to-digital converter or a filter. A sensor device may beintegrated on a single chip, although in other embodiments a pluralityof chips or also components external to a chip may be used forimplementing a sensor device.

According to the embodiments, a photodetector array is used to measurethe reflected light. The photodetector array may be a one-dimensional(1D) array that consists of multiple rows of photodetectors (pixels)arranged in a single column or a two-dimensional (2D) array thatconsists of multiple rows and columns of photodetectors arranged in agrid-like arrangement. Each photodetector is configured to generate anelectrical signal (e.g., an electrical pulse) in response to receivinglight. Each photodetector may be read out as measurement signal in theform of raw analog data.

The photodetector array can be any of a number of photodetector types;including avalanche photodiodes (APD), photocells, and/or otherphotodiode devices.

Imaging sensors such as charge-coupled devices (CCDs) can be thephotodetectors. As provided herein, “photodiodes”, “photodetectors”, and“pixels” are used interchangeably and represent the active area or thesensitive area of the photodetector array capable of detecting photons.In the examples provided herein, the photodetector array is a 2D arrayof APD pixels, but this is merely intended to serve as one example of aphotodetector array and should not be construed as limiting.

Metal areas described herein are a non-sensitive or non-active area thatis arranged around a periphery of each pixel. The metal areas mayinclude metal structures used to produce an electric field used totailor one or more properties of the photodetector array. Additionally,the metal areas may include metal lines, metal contacts, etc. that maybe used for electrical pathways to carry electrical signals. Forexample, the metal areas may be used to activate a pixel and/or read outelectrical signals generated by a pixel. The metal areas may beconsidered a highly reflective area with respect to received light. Forexample, the metal areas may have a reflectivity that meets or exceeds70%.

FIGS. 1A-1C illustrate a process of manufacturing a photodetector device100 according to one or more embodiments. The photodetector device 100includes a transparent substrate 11 (e.g., a transparent plate) disposedover a photodetector array 12.

The transparent substrate 11 is made of a transparent material, such asglass, that permits the transmission of light therethrough.

The photodetector array 12 includes an array of photodetectorscomprising a plurality of photodetectors 13. The photodetector array 12further includes a plurality of metal structures 14 arranged between thephotodetectors 13 of the photodetector array 12. The plurality of metalstructures 14 are arranged in a first (metal) pattern. For example, theplurality of metal structures 14 may be arranged in a grid pattern.Furthermore, the plurality of metal structures 14 may be coupledtogether to form one-piece integral construction. That is, they may forma single member.

The photodetector device 100 further includes an antireflective coating15 (e.g., a black coating) applied to a front surface 16 of thetransparent substrate 11 in a second (antireflective coating) patternthat coincides and is aligned with the first pattern of the plurality ofmetal structures 14. In other words, the second pattern matches thefirst pattern. The transparent substrate 11 is disposed over a surfaceof the photodetector array 12 such that the front surface 16 facestowards the sensitive regions of the photodetector array 12. Theantireflective coating 15 is aligned with the plurality of metalstructures 14 such that the second pattern is aligned with the firstpattern. As a result, the antireflective coating 15 is disposed onto theplurality of metal structures 14 as serves as a shadowing mask such thatthe antireflective coating 15 absorbs incoming light and prevents theincoming light from reaching the plurality of metal structures 14. As aresult, optical crosstalk that could be caused by the plurality of metalstructures 14 is prevented.

The antireflective coating 15 may be any material that has anantireflective property sufficient to absorb light to reduce oreliminate optical crosstalk may be used. For example, the material maybe at least 80% antireflective/absorptive (i.e., less than 20%reflective), and more preferably, at least 90% antireflective/absorptive(i.e., less than 10% reflective), and even more preferably, at least 95%antireflective/absorptive (i.e., less than 5% reflective). Reflectivityis the amount or percentage of light or radiation that is reflected by amaterial and anti-reflectivity is the amount or percentage of light orradiation that is absorbed by a material. Thus, a highly antireflectivematerial is defined as a highly absorptive material, and varying degreesof antireflectivity correspond to varying degrees of absorptivity. To beclear, antireflectivity does not correspond to transparency.

FIG. 1A illustrates a step of manufacturing the photodetector device 100according to one or more embodiments. In particular, FIG. 1A illustratesapplying the antireflective coating 15 to the front surface 16 of thetransparent substrate 11 according to the second pattern of theantireflective coating.

FIG. 1B illustrates another step of manufacturing the photodetectordevice 100 according to one or more embodiments. In particular, FIG. 1Billustrates a top view of aligning the transparent plate 11, having theantireflective coating 15 applied thereto, with the photodetector array12 such that the second pattern of the antireflective coating is alignedwith the first pattern of the plurality of metal structures 14.

FIG. 1C illustrates another step of manufacturing the photodetectordevice 100 according to one or more embodiments. In particular, FIG. 1Cillustrates, once the second pattern of the antireflective coating isaligned with the first pattern of the plurality of metal structures 14,disposing the transparent plate 11 with the antireflective coating 15onto the photodetector array 12 such that the antireflective coating 15covers the plurality of metal structures 14. The transparent plate 11 iscoupled to the photodetector array 12.

The antireflective coating 15 may be disposed onto the plurality ofmetal structures 14 such that the antireflective coating 5 is in directcontact with the plurality of metal structures 14. As such, there may bea small gap 17 between the transparent plate 11 and the photodetectorarray 12. This gap 17 may be filled with an adhesive to bind thetransparent plate 11 and the photodetector array 12 together. FIG. 1Cillustrates a cross-sectional view of the final assembled photodetectordevice 100.

FIG. 2 illustrates a cross-sectional view of an assembled photodetectordevice 200 according to one or more embodiments. In particular, thephotodetector device 200 is similar to the photodetector device 100illustrated in FIG. 1C except the transparent plate 11 includespatterned trenches 21. In particular, prior to applying theantireflective coating 15, the transparent plate 11 is etched withtrenches 21 according to the second pattern to match the first patternof the plurality of metal structures 14. Thus, the trenches 21 areformed in the transparent substrate 11 at the front surface 16 andextend vertically into the transparent substrate 11 from the frontsurface 16. The trenches 21 may be coupled together to form a unitarytrench according to the second pattern.

The trenches 21 are then filled with the antireflective coating 15 suchthat the antireflective coating 15 is embedded within the transparentsubstrate 11. As a result of the patterned trenches 21, theantireflective coating 15 takes on the pattern of the trenches, and thusthe pattern of the plurality of metal structures 14.

The outer or exposed surface of the antireflective coating 15 is planarwith the front surface 16 of the transparent substrate 11.

The pattern of the trenches/antireflective coating is then aligned withpattern of the plurality of metal structures 14 in a similar mannerillustrated in FIG. 1B.

Once the patterns are aligned, the transparent plate 11 with theantireflective coating 15 is disposed onto the photodetector array 12such that the antireflective coating 15 covers the plurality of metalstructures 14. The antireflective coating 15 may be disposed onto theplurality of metal structures 14 such that the antireflective coating 15is in direct contact with the plurality of metal structures 14. Inaddition, the transparent plate 11 may be arranged on the front surface16 of the photodetector array 12 to be in direct contact with thephotodetectors 13, with no gap therebetween, due to the outer or exposedsurface of the antireflective coating 15 being planar with the frontsurface 16 of the transparent substrate 11. Alternatively, an adhesivemay be applied between the transparent plate 11 and the photodetectors13 to bind the transparent plate 11 and the photodetector array 12together.

FIG. 3 illustrates a cross-sectional view of an assembled photodetectordevice 300 according to one or more embodiments. In particular, thephotodetector device 300 is similar to the photodetector device 200illustrated in FIG. 2 except the transparent plate 11 includes patterneddeep trenches 31. In particular, prior to applying the antireflectivecoating 15, the transparent plate 11 is etched with deep trenches 31according to the second pattern to match the first pattern of theplurality of metal structures 14. Thus, the deep trenches 21 are formedin the transparent substrate 11 at the front surface 16 and extendvertically into the transparent substrate 11 from the front surface 16.However, in contrast to the trenches 21 shown in FIG. 2, the deeptrenches 31 may extend further into the transparent substrate 11 toallow for an air gap 32 between the antireflective coating 15 and themetal structures 14.

Thus, deep trenches 31 are only partially filled with the antireflectivecoating 15 after being formed such that the antireflective coating 15 isembedded entirely within the transparent substrate 11. As a result ofthe patterned trenches 31, the antireflective coating 15 takes on thepattern of the trenches, and thus the pattern of the plurality of metalstructures 14. However, as a result of only partially filing thetrenches 31, the antireflective coating 15 is not planar with the frontsurface 16. Instead, the vertical dimension (e.g., thickness) of theantireflective coating 15 is less than the vertical dimension (e.g.,depth) of the trenches 31.

Once the deep trenches 31 are partially filled with antireflectivecoating 15, the pattern of the trenches/antireflective coating is thenaligned with pattern of the plurality of metal structures 14 in asimilar manner illustrated in FIG. 1B.

Once the patterns are aligned, the transparent plate 11 with theantireflective coating 15 is disposed onto the photodetector array 12such that the antireflective coating 15 covers the plurality of metalstructures 14. However, since the thickness of the antireflectivecoating 15 is less than the depth of the trenches 31, an air gap 32 isformed between the antireflective coating 15 and the metal structures14. The air gap 32 may be desirable to avoid the antireflective coating15 coming in contacts with the metal structures 14. In particular, theantireflective coating 15 may have a non-zero conductivity which mayalter the electric field generated by the metal structures 14 andthereby change the electrical parameters of the photodetectors 13 in anunintended or undesirable way. Thus, by preventing contact, theelectrical parameters of the photodetectors 13 may be maintained asintended.

In addition, the transparent plate 11 may be arranged on the frontsurface 16 of the photodetector array 12 to be in direct contact withthe photodetectors 13, with no gap therebetween, due to theantireflective coating 15 being fully embedded within the transparentsubstrate 11. Alternatively, an adhesive may be applied between thetransparent plate 11 and the photodetectors 13 to bind the transparentplate 11 and the photodetector array 12 together.

FIGS. 4A-4C illustrate a process of manufacturing a photodetector device400 according to one or more embodiments. Similar to the photodetectordevice 100, the photodetector device 400 includes a transparentsubstrate 11 (e.g., a transparent plate) disposed over a photodetectorarray 12.

However, instead of using an antireflective coating, the photodetectordevice 400 uses microsteering structures 41, which may be referred to asdiffusion structures 41, formed in the transparent substrate 11 by, forexample, etching. The diffusion structures 41 may be formed in a pattern(steering structure pattern) that coincides and is aligned with thefirst pattern of the plurality of metal structures 14. In other words,the steering structure pattern is a second pattern that matches thefirst pattern. The diffusion structures 41 are configured to steer(i.e., redirect) light that is incident thereon away from an adjacentmetal structure 14 and steer the light towards a photodetector 13 thatis arranged immediately adjacent to the respective diffusion structure41. For example, as illustrated in FIG. 4C, light that is incident on adiffusion structure 41 is reflected back at surface 18 of thetransparent substrate 11, which reflects the light back at the adjacentphotodetector 13 by internal reflection.

The transparent substrate 11 is disposed over a surface of thephotodetector array 12 such that the front surface 16 faces towards thesensitive regions of the photodetector array 12. The diffusionstructures 41 are aligned with the plurality of metal structures 14 suchthat the second pattern is aligned with the first pattern. As a result,the diffusion structures 41 are disposed over the plurality of metalstructures 14 as serves as a steering structure mask such that thediffusion structures 41 steer incoming light to adjacent photodetectors13 and prevent the incoming light from reaching the metal structures 14.As a result, optical crosstalk that could be caused by the metalstructures 14 is prevented.

FIG. 4A illustrates a step of manufacturing the photodetector device 400according to one or more embodiments. In particular, FIG. 4A illustratesforming the diffusion structures 41 at the front surface 16 of thetransparent substrate 11 according to the second pattern. Thus, thediffusion structures 41 extend from the front surface 16 into thetransparent substrate 11. Etching may be used to form the diffusionstructures 41.

FIG. 4B illustrates another step of manufacturing the photodetectordevice 400 according to one or more embodiments. In particular, FIG. 4Billustrates a top view of aligning the transparent plate 11, having thediffusion structures 41 formed, with the photodetector array 12 suchthat the second pattern of the diffusion structures 41 is aligned withthe first pattern of the metal structures 14.

FIG. 4C illustrates another step of manufacturing the photodetectordevice 400 according to one or more embodiments. FIG. 4C illustrates across-sectional view of the final assembled photodetector device 400. Inparticular, FIG. 4C illustrates, once the second pattern of thediffusion structures 41 is aligned with the first pattern of theplurality of metal structures 14, disposing the transparent plate 11with the diffusion structures 41 onto the photodetector array 12 suchthat the diffusion structures 41 cover the metal structures 14.

In addition, the transparent plate 11 may be arranged on the frontsurface 16 of the photodetector array 12 to be in direct contact withthe photodetectors 13, with no gap therebetween. Alternatively, anadhesive may be applied between the transparent plate 11 and thephotodetectors 13 to bind the transparent plate 11 and the photodetectorarray 12 together.

FIG. 5 illustrates a cross-sectional view of an assembled photodetectordevice 500 according to one or more embodiments. In particular, thephotodetector device 500 is similar to the photodetector device 400illustrated in FIG. 4C except the trenches (diffusion trenches) of thediffusion structures 41 are filled with antireflective coating 15, whichmay be performed in between steps illustrated by FIGS. 4A and 4B.

As a result, the trenches of the diffusion structures 41 being filledwith the antireflective coating 15, the antireflective coating 15 isembedded within the transparent substrate 11. As a result,antireflective coating 15 takes on the pattern of the diffusionstructures 41, and thus the pattern of the plurality of metal structures14.

The outer or exposed surface of the antireflective coating 15 is planarwith the front surface 16 of the transparent substrate 11.

The pattern of the diffusion structures/antireflective coating is thenaligned with pattern of the metal structures 14 in a similar mannerillustrated in FIG. 4B.

Once the patterns are aligned, the transparent plate 11 with theantireflective coating 15 and diffusion structures 41 is disposed ontothe photodetector array 12 such that the antireflective coating 15 andthe diffusion structures 41 cover the metal structures 14.

The antireflective coating 15 may be disposed onto the metal structures14 such that the antireflective coating 15 is in direct contact with themetal structures 14. In addition, the transparent plate 11 may bearranged on the front surface 16 of the photodetector array 12 to be indirect contact with the photodetectors 13, with no gap therebetween, dueto the outer or exposed surface of the antireflective coating 15 beingplanar with the front surface 16 of the transparent substrate 11.Alternatively, an adhesive may be applied between the transparent plate11 and the photodetectors 13 to bind the transparent plate 11 and thephotodetector array 12 together.

The following additional embodiments are provided:

1. A method of manufacturing a photodetector device, the methodcomprising: providing a photodetector array comprising an array ofphotodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; applying anantireflective coating to a surface of a transparent substrate, theantireflective coating being patterned according to a second patternthat matches the first pattern; aligning the transparent substrate overthe photodetector array such that the first pattern is aligned with thesecond pattern; and coupling the transparent substrate to thephotodetector array such that the antireflective coating covers theplurality of metal structures.

2. The method of embodiment 1, wherein coupling the transparentsubstrate to the photodetector array includes arranging theantireflective coating onto the plurality of metal structures such thatthe antireflective coating is in contact with the plurality of metalstructures.

3. The method of embodiment 1, wherein the antireflective coating is ablack coating.

4. The method of embodiment 1, wherein the first pattern and the secondpattern have a grid pattern.

5. The method of embodiment 1, wherein the plurality of metal structuresare coupled together to form one-piece integral construction.

6. A photodetector device, comprising:

a photodetector array comprising an array of photodetectors and aplurality of metal structures arranged between photodetectors of thearray of photodetectors, wherein the plurality of metal structures arearranged in a first pattern; and a transparent substrate comprising aplurality of trenches being patterned according to a second pattern thatmatches the first pattern and at least partially filled with anantireflective material such that the antireflective material takes onthe second pattern, wherein the transparent substrate and thephotodetector array are coupled together such that the first pattern isaligned with the second pattern and the antireflective material coversthe plurality of metal structures.

7. The photodetector device of embodiment 6, wherein the plurality oftrenches are partially filled with the antireflective material such thatthe antireflective material is embedded entirely within the transparentsubstrate.

8. The photodetector device of embodiment 7, further comprising:

at least one air gap formed between the antireflective material and eachof the plurality of metal structures.

9. The photodetector device of embodiment 8, wherein the antireflectivematerial is enclosed within the plurality of trenches and enclosedbetween the transparent plate and the plurality of metal structures.

10. The photodetector device of embodiment 6, wherein the plurality oftrenches are coupled together to form a unitary trench.

11. The photodetector device of embodiment 6, wherein the plurality oftrenches extend from a surface of the transparent substrate into thetransparent substrate and the surface of the transparent substrate iscoupled to the array of photodetectors.

12. The photodetector device of embodiment 6, wherein: the plurality oftrenches extend from a surface of the transparent substrate into thetransparent substrate, the plurality of trenches are completely filledwith the antireflective material such that a surface of theantireflective material is planar with the surface of the transparentsubstrate, and the surface of the antireflective material is coupled tothe plurality of metal structures.

13. The photodetector device of embodiment 12, wherein the surface ofthe antireflective material is in contact with the plurality of metalstructures.

14. A method of manufacturing a photodetector device, the methodcomprising: providing a photodetector array comprising an array ofphotodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; forming a plurality oftrenches in a transparent substrate, the plurality of trenches beingpatterned according to a second pattern that matches the first pattern;at least partially filing the plurality of trenches with anantireflective material such that the antireflective material takes onthe second pattern; aligning the transparent substrate over thephotodetector array such that the first pattern is aligned with thesecond pattern; and coupling the transparent substrate to thephotodetector array such that the antireflective material covers theplurality of metal structures.

15. The method of embodiment 14, wherein at least partially filing theplurality of trenches with the antireflective material comprisespartially filling the plurality of trenches with the antireflectivematerial such that the antireflective material is embedded entirelywithin the transparent substrate.

16. The method of embodiment 15, further comprising:

forming at least one air gap between the antireflective material andeach of the plurality of metal structures by coupling the transparentsubstrate to the photodetector array.

17. The method of embodiment 16, wherein the antireflective material isenclosed within the plurality of trenches and enclosed between thetransparent plate and the plurality of metal structures.

18. The method of embodiment 14, wherein forming the plurality oftrenches in the transparent substrate comprises forming the plurality oftrenches as a unitary trench.

19. The method of embodiment 14, wherein: forming the plurality oftrenches in the transparent substrate comprises extending the pluralityof trenches from a surface of the transparent substrate into thetransparent substrate, and coupling the transparent substrate to thephotodetector array comprises coupling the surface of the transparentsubstrate to the array of photodetectors.

20. The method of embodiment 14, wherein: forming the plurality oftrenches in the transparent substrate comprises extending the pluralityof trenches from a surface of the transparent substrate into thetransparent substrate, at least partially filing the plurality oftrenches with the antireflective material comprises completely fillingthe plurality of trenches with the antireflective material such that asurface of the antireflective material is planar with the surface of thetransparent substrate, and coupling the transparent substrate to thephotodetector array comprises coupling the surface of the antireflectivematerial to the plurality of metal structures.

21. The method of embodiment 20, wherein the surface of theantireflective material is in contact with the plurality of metalstructures.

22. A photodetector device, comprising: a photodetector array comprisingan array of photodetectors and a plurality of metal structures arrangedbetween photodetectors of the array of photodetectors, wherein theplurality of metal structures are arranged in a first pattern; and atransparent substrate comprising a plurality of diffusion structuresbeing patterned according to a second pattern that matches the firstpattern, wherein each of the plurality of diffusion structures isconfigured to redirect light that is incident thereon, wherein thetransparent substrate and the photodetector array are coupled togethersuch that the first pattern is aligned with the second pattern and theplurality of diffusion structures covers the plurality of metalstructures.

23. The photodetector device of embodiment 22, wherein each of theplurality of diffusion structures is arranged adjacent to at least oneof the plurality of metal structures and is configured to redirect thelight that is incident thereon away from an adjacent metal structure andtowards an adjacent photodetector.

24. The photodetector device of embodiment 22, wherein: each of theplurality of diffusion structures comprises a plurality of diffusiontrenches that extend from a surface of the transparent substrate intothe transparent substrate, and the surface of the transparent substrateis coupled to the array of photodetectors.

25. The photodetector device of embodiment 24, further comprising: anantireflective material, wherein the plurality of diffusion trenches ofeach of the plurality of diffusion structures are filled with theantireflective material such that a surface of the antireflectivematerial is planar with the surface of the transparent substrate, andthe surface of the antireflective material is coupled to the pluralityof metal structures.

26. The photodetector device of embodiment 25, wherein the surface ofthe antireflective material is in contact with the plurality of metalstructures.

27. The photodetector device of embodiment 22, further comprising: atleast one air gap formed between the plurality of diffusion structuresand each of the plurality of metal structures.

28. The photodetector device of embodiment 22, wherein: each of theplurality of diffusion structures comprises a plurality of diffusiontrenches that extend from a surface of the transparent substrate intothe transparent substrate, wherein the plurality of diffusion trenchesform at least one air gap between the plurality of diffusion structuresand each of the plurality of metal structures.

29. A method of manufacturing a photodetector device, the methodcomprising: providing a photodetector array comprising an array ofphotodetectors and a plurality of metal structures arranged betweenphotodetectors of the array of photodetectors, wherein the plurality ofmetal structures are arranged in a first pattern; forming a plurality ofdiffusion structures in a transparent substrate, the plurality ofdiffusion structures being patterned according to a second pattern thatmatches the first pattern, wherein each of the plurality of diffusionstructures is configured to redirect light that is incident thereon;aligning the transparent substrate over the photodetector array suchthat the first pattern is aligned with the second pattern; and couplingthe transparent substrate to the photodetector array such that theplurality of diffusion structures covers the plurality of metalstructures.

30. The method of embodiment 29, wherein coupling the transparentsubstrate to the photodetector array includes arranging each of theplurality of diffusion adjacent to at least one of the plurality ofmetal structures, wherein each of the plurality of diffusion structuresis configured to redirect the light that is incident thereon away froman adjacent metal structure and towards an adjacent photodetector.

31. The photodetector device of embodiment 29, wherein: forming theplurality of diffusion structures in the transparent substrate comprisesforming, for each of the plurality of diffusion structures, a pluralityof diffusion trenches that extend from a surface of the transparentsubstrate into the transparent substrate, and coupling the transparentsubstrate to the photodetector array includes coupling the surface ofthe transparent substrate to the array of photodetectors.

32. The method of embodiment 31, further comprising: filling theplurality of diffusion trenches of each of the plurality of diffusionstructures with an antireflective material such that a surface of theantireflective material is planar with the surface of the transparentsubstrate, and coupling the transparent substrate to the photodetectorarray includes coupling the surface of the antireflective material tothe plurality of metal structures.

33. The method of embodiment 32, wherein the surface of theantireflective material is in contact with the plurality of metalstructures.

34. The method of embodiment 31, wherein coupling the transparentsubstrate to the photodetector array includes forming at least one airgap between the plurality of diffusion structures and each of theplurality of metal structures.

35. The method of embodiment 29, wherein: forming the plurality ofdiffusion structures in the transparent substrate comprises forming, foreach of the plurality of diffusion structures, a plurality of diffusiontrenches that extend from a surface of the transparent substrate intothe transparent substrate, and coupling the transparent substrate to thephotodetector array includes forming at least one air gap by theplurality of diffusion trenches, the at least one air gap being formedbetween the plurality of diffusion structures and each of the pluralityof metal structures.

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method of manufacturing, where the addition of eachelement corresponds to a method step or a feature of a method step.Analogously, aspects described in the context of a method step alsorepresent a description of a corresponding block or item or feature of acorresponding apparatus. Some or all of the method steps may be executedby (or using) a hardware apparatus, like for example, a microprocessor,a programmable computer, or an electronic circuit. In some embodiments,some one or more of the method steps may be executed by such anapparatus.

Further, it is to be understood that the disclosure of multiple acts orfunctions disclosed in the specification or claims may not be construedas to be within the specific order. Therefore, the disclosure ofmultiple acts or functions will not limit these to a particular orderunless such acts or functions are not interchangeable for technicalreasons. Furthermore, in some embodiments a single act may include ormay be broken into multiple sub acts. Such sub acts may be included andpart of the disclosure of this single act unless explicitly excluded.

Furthermore, the description and drawings merely illustrate theprinciples of the disclosure. It will thus be appreciated that thoseskilled in the art will be able to devise various arrangements that,although not explicitly described or shown herein, embody the principlesof the disclosure and are included within its spirit and scope.Furthermore, all examples recited herein are principally intendedexpressly to be only for pedagogical purposes to aid in theunderstanding of the principles of the disclosure and the conceptscontributed to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass equivalents thereof. Thus, it is understood thatmodifications and variations of the arrangements and the detailsdescribed herein will be apparent to others skilled in the art.

Furthermore, the following claims are hereby incorporated into thedetailed description, where each claim may stand on its own as aseparate example embodiment. While each claim may stand on its own as aseparate example embodiment, it is to be noted that—although a dependentclaim may refer in the claims to a specific combination with one or moreother claims—other example embodiments may also include a combination ofthe dependent claim with the subject matter of each other dependent orindependent claim. Such combinations are proposed herein unless it isstated that a specific combination is not intended. Furthermore, it isintended to include also features of a claim to any other independentclaim even if this claim is not directly made dependent to theindependent claim.

What is claimed is:
 1. A method of manufacturing a photodetector device,the method comprising: providing a photodetector array comprising anarray of photodetectors and a plurality of metal structures arrangedlaterally between photodetectors of the array of photodetectors, whereinthe photodetectors are co-planar with the plurality of metal structures,and wherein the plurality of metal structures are arranged in a firstpattern; applying an antireflective coating to a surface of atransparent substrate, the antireflective coating being patternedaccording to a second pattern that matches the first pattern; aligningthe transparent substrate over the photodetector array such that thefirst pattern is aligned with the second pattern; and coupling thetransparent substrate to the photodetector array such that theantireflective coating covers the plurality of metal structures.
 2. Themethod of claim 1, wherein coupling the transparent substrate to thephotodetector array includes arranging the antireflective coating ontothe plurality of metal structures such that the antireflective coatingis in contact with the plurality of metal structures.
 3. The method ofclaim 1, wherein the antireflective coating is a black coating.
 4. Themethod of claim 1, wherein the first pattern and the second pattern havea grid pattern.
 5. The method of claim 1, wherein lateral sides of theplurality of metal structures are in contact with lateral sides of thephotodetectors.
 6. The method of claim 1, wherein each metal structureof the plurality of metal structures comprises at least one lateral sidethat is in direct contact with a lateral side of an adjacentphotodetector of the array of photodetectors.
 7. The method of claim 1,wherein the plurality of metal structures are connected together to forma unitary metal structure.
 8. The method of claim 1, wherein theplurality of metal structures are interleaved with the photodetectors ofthe array of photodetectors on an alternating, one-by-one basis.